Test building images from a private repo

(cherry picked from commit 7af3418)

Author: m-bull

.github/workflows/stackhpc-container-image-build.yml

@@ -230,6 +230,8 @@ jobs:
           kayobe overcloud container image build $args
         env:
           KAYOBE_VAULT_PASSWORD: ${{ secrets.KAYOBE_VAULT_PASSWORD }}
+          CI_GITHUB_USERNAME: "stackhpc-ci"
+          CI_GITHUB_TOKEN: ${{ secrets.TEMP_STACKHPC_CI_CLONE_REPO_TOKEN }}
         if: inputs.overcloud
 
       - name: Copy build configs to output directory

etc/kayobe/kolla.yml

@@ -143,6 +143,10 @@ kolla_sources:
     type: git
     location: https://github.com/stackhpc/stackhpc-inspector-plugins.git
     reference: 1.3.0
+  keystone-base:
+    type: git
+    location: https://{{ lookup('env', 'CI_GITHUB_USERNAME') }}:{{ lookup('env', 'CI_GITHUB_TOKEN') }}@github.com/stackhpc/keystone-private.git
+    reference: 2024.1-2119646
   magnum-base:
     type: git
     location: https://github.com/stackhpc/magnum.git